I. Field
The present disclosure relates generally to electronics, and more specifically to an operational transconductance amplifier (OTA).
II. Background
An OTA is a circuit that receives an input voltage and provides an output current. An OTA may be used for switched-capacitor circuits as well as other circuits. A switched-capacitor circuit is a circuit that performs discrete-time signal processing by transferring charges into and out of capacitors when switches are opened and closed. An OTA is typically used as an amplifier to provide charging and discharging current in a switched-capacitor circuit. A transfer function for a switched-capacitor circuit may be defined based on ratios of capacitor sizes, which may be more accurately achieved than absolute capacitor sizes in an integrated circuit (IC).
An OTA may be implemented in complementary metal oxide semiconductor (CMOS) in order to obtain small size and low power consumption. However, the OTA may have small gain and small output signal swing if implemented with a low-voltage small-geometry CMOS process. The small gain may result in inaccurate charge transfer, and the small output signal swing may limit the dynamic range of a switched-capacitor circuit. There is therefore a need in the art for an OTA with large gain and large output signal swing.